Effects of methylene blue on rat infraorbital nerve / 实用口腔医学杂志

ABSTRACT

?Objective: To examine the morphologic changes produced by extranueral injection of methylene blue around rat infraorbital nerve. Methods: Under direct vision, 50 ?l of methylene blue at the concentration of 20 g/L was injected extranuerally into the infraorbital foramen on one side of the maxillar bone of each of 32 rats; physiological saline was used as the control on the contralateral side of each animal. Animals were killed at 3 days, 2, 4, 8 and 14 weeks after the application of methylene blue respectively. The infraorbital nerve specimens were examined by light and electron microscopes. Results:Axolysis and demyelination were found in the outer zone of the nerve bundles, and a few of centrally located axons were damaged in 2 and 3 weeks. 4 weeks later,a few of regenerated fibers were observed. Wallerian degeneration still remained and more regenerated fibers were found in 14 weeks. The sheath of myelinated fibers became twisted, thick and dissolved. The axonal changes characterized by either swelling, shrinking or vacuolization of axoplasm. Lysosome could be seen in the axons. The changes of myelinated fibers were more evident than that of demyelinated fibers. At the later stage, the regularly regenerated fibers with thin sheath could be seen. No change was observed in the Schwann cells. Conclusion: 20 g/L methylene blue can result in the changes of the sheath and axons of nerve fibers